How to know whether any process is bound to a Unix domain socket?

Question

I'm writing a Unix domain socket server for Linux.

A peculiarity of Unix domain sockets I quickly found out is that, while creating a listening Unix socket creates the matching filesystem entry, closing the socket doesn't remove it. Moreover, until the filesystem entry is removed manually, it's not possible to bind() a socket to the same path again : bind() fails with EADDRINUSE if the path it is given already exists in the filesystem.

As a consequence, the socket's filesystem entry needs to be unlink()'ed on server shutdown to avoid getting EADDRINUSE on server restart. However, this cannot always be done (i.e.: server crash). Most FAQs, forum posts, Q&A websites I found only advise, as a workaround, to unlink() the socket prior to calling bind(). In this case however, it becomes desirable to know whether a process is bound to this socket before unlink()'ing it.

Indeed, unlink()'ing a Unix socket while a process is still bound to it and then re-creating the listening socket doesn't raise any error. As a result, however, the old server process is still running but unreachable : the old listening socket is "masked" by the new one. This behavior has to be avoided.

Ideally, using Unix domain sockets, the socket API should have exposed the same "mutual exclusion" behavior that is exposed when binding TCP or UDP sockets : "I want to bind socket S to address A; if a process is already bound to this address, just complain !" Unfortunately this is not the case...

Is there a way to enforce this "mutual exclusion" behavior ? Or, given a filesystem path, is there a way to know, via the socket API, whether any process on the system has a Unix domain socket bound to this path ? Should I use a synchronization primitive external to the socket API (flock(), ...) ? Or am I missing something ?

Thanks for your suggestions.

Note : Linux's abstract namespace Unix sockets seem to solve this issue, as there is no filesystem entry to unlink(). However, the server I'm writing aims to be generic : it must be robust against both types of Unix domain sockets, as I am not responsible for choosing listening addresses.